Motor control.



J- C. CLENDENIN.

MOTOR CONTROL.

APPLICATION FILED FEB. Z1. 19!].

Fig I.

lnven'tor' I d-ohn CLCIencleni'n Patented Jan. 8, 1918.

m TED STATES PATENT OFF-Ion.

JOHN G. CLENDENIN, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

oron contract.

and useful Improvements in Motor Controlls, of which the following is a specification.

My invention relates to the control of electric motors and. 't provides improved means whereby the motors may be started and stopped and. be generally controlled in a safe, reliable and efficient manner.

My invention has a articular utility in the control of the electric driving motors of vehicles or tractors such as fire engines and the like, where fronnthe necessities of the case. it is required that the rotating elements of the driving motors shall be separate and independent in so far as their respective speeds of rotation are concerned. The necessity for such a control in the case of a fire engine, for instance, arises from the fact that the drrve must be placed on the two front wheels with a driving motor on each of the front wheels. An element of danger is thus introduced in case the motors are connected in parallel, since if one motor is de energized the other motor will have a clan gerous tendency to instantly deflect the tractor from its path of travel. Of course. where the motors are connected in series, such a dangerous conditionwill not occur because opening the circuits to either driving motor opens the circuit to both motors. l-lowever, in order to operate the motors the most satisfactorily and efliciently, it is required that a series parallel control be provided 'for starting and for certain operating conditions, the parallel arrangement being used for normal running conditions and the series arrangement used for starting and for reduced speed running in taking heavy grades or where the road bed'is rough.

VJ ()ne of the objects of my invention is to provide a control for electric'motors, such as the driving motors of a tractor or. the like, wherein, While the motors are connectcdin parallel, upon the occurrence of abnormal,

circuit conditions such as the deenergization same.

of'a portion of the motors, the other-portion Specification of LettersPatent. Patented Jan. 8, 1918.

i I Application filed February 21, 191?. Serial No, 150,238. r

of the motors will be automatically and to all i I intents and purposes simultaneously deencrgized to avoid the dangerous condition above pointed out. A further object of my invention is to provide aseries parallel control for the motors, so arranged that theniotors will be protected as above pointed out while they are in the parallel relation, but will not be automatically de'c nergized in making the transition from the one relation o the other.

In carrying my invention into efl'ect I provide a controller for connecting the motors in series or parallel, preferably a controller which shunts one of the motors during the transition to make the transition from the one relation to the other without opening the motor circuits. In the circuit leading from the source of supply to the motors, I provide a circuit breaker which has a plurality of series coils, each coil responsive to the current in a motor circuit,

the coils normally tending to neutralize each. other and having no tendency to open the breaker as long as the current flowing through each coil circuit is substantially the \Vhen the motors are connected in parallel, in case either motor is deiinergized, its corresponding breaker coil is deener gized, and the other coil being energized will operate to trip the breaker. While the transition from series to parallel or parallel to series is being made and one of the motors is shunted in the well known manner, it can be seen that the breaker coil which is in. series with the motor which is being shunted would be practically without current while" the other coil is fully energized; The breaker would accordingly be tripped during this transition period if some preventive means were not provided. In order to take care of this feature, I preferably place a shunt around the breaker coil of the motor which is energized during-the transition, thereby rleiinergizing both breaker coils and permitting the breaker to remain closed. Simultaneously with completing the desired connection of the motors, the shunt from this coil is removedythus energizing both coils to neutralize each other and permit the breaker to remain closed as long as both motors are energized.

For a better'understanding of my invention, refere'nceis had to the following description taken in connection with the accompanying drawing. Referring to the drawing, Fi ire 1 shows, diagrammatically,

a system 0 motor control embodying my invention, and Figs. 2 to 5 inclusive-are'simplified diagrams of the various connections made by the operation of the series parallel controller shown in Fig. 1.

Referring to Fig. 1, each of the driving motors M and M preferably of the series wound type as shown in the drawing, is to be understood as having its rotated element separately connected to drive one of the front wheels of a vehicle. The rotating element of each motor is adapted to be connected to a vehicle wheel so as to be capable of independent rotation so. as to take care of difl'erences in speed required of the motorswhen the vehicle is taking turns, etc. The

motors receive energy from any suitable source of supply, that shown in the drawings being the generator G which is driven by any suitable primemover, as for instance .an' internal combustion engine (not shown). The speed of the motors may be varied by varying the voltage of the-generator by any suitable means, the variable resistance R in the generator field circuit being provided for that purpose in the arrangement shown in the drawings. It will also be understood that the voltage of the generator and thereby the speed of the driving motors may like,- wise be varied by controlling the speed of the prime mover. In order to secure a more satisfactory control of the motor speeds, a series parallel controller C is provided. This controller is of the type which. changes from the series to the parallel relation of the motors and vice versa without opening the motor circuits, this being accomplished by shunting the motor M during the series parallel transition. Inthe circuit from the source of supply (the generator G) to the driving motors there is provided an automatic circuit breaker GB for deinergizing bqth motors upon the occurrence of abnormal circuit conditions such as a deenergizationof one of the motors when they are con- I nected in the parallel relation, thus avoiding the dangerous tendency of the other motor to deflect the vehicle from its path of travel.

Tripping means is provided for this circuit breaker andfcomprises the seriescoils 1 and '2 included inthe circuits of the motors M the parallel relation and either motor is deenergized. When either motor is deiinergized, its respective circuit breaker coil is denergized and the other breaker coil is permitted to operate the pivoted latch 3 and trip the breaker. The series parallel controller C is shown in the off position and the arrangement is such that moving the controller to the first operative position to the right connects the motors in series, after which,movin the controller to the 'second operative position connects the motors in parallel without opening the motor circuits, the motor M and its circuit breaker coil' 1 being shunted' during the series parallel transition and the circuit breaker coil 2 in the circuit of M being simultaneously shunted through the resistance 4 duringthis' transition period to prevent the tripping of the breaker. Moving the controller from the neutral position toward the left reverses the motors by reversin the current throughv their field circuits, an causes the vehicle to run in the reverse direction.

The operationof 'myfinvention as thus constructed and arranged is as. follows Moving the controller to the first operative osition' to the right energizes the motors in series from the generator G with the tripping coils 1 and 2 of the circuit breaker connected in seriesrthe connections being as shown in simplified form in Fig. 2. The

coils 1 and 2 neutralize each other and there.

fore have no tendency to open the breaker.

In moving the controller'from the first opthe right, the motors are-connected in parallel to the source of supply as shown in Fig. 4, the shunt circuit including the resistance 4 which had been placed around the tripping coil 2 being removed, thereby energizing both coils so as to neutralize each other and have no tendency toopen the breaker aslong as both of the motors are energized. Any substantial change in the energization ofeither motor, such as the opening of oneofthe motor circuits due to accidental causes, Wlll cause the circult breaker coil which is fully energized to trip the breaker and open the circuit to, hot

motors. thereby preventing the tractor from being deflected from its ,course.

Moving the controller from the parallel a through the series fields of the motors and causes the motors to reverse their-direction of rotation in a Well understood manner. The connections for the reverse operatlon are as shown in Fig. 5. a l

' While I have described my invention as embodied in concrete form and as operating in a specific manner in accordance with the provisions of the patent statutes, it should be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

What I claim as newand desire to secure by Letters Patent of the United States is:

1.. The combination with a plurality of electric motors connected in parallel relation to a source of supply, each motor separately driving a vehicle wheel, of automatic means operated responsively to the deenerz gization of a portion of the motors, for deenergizing all the motors.

2. In combination, a plurality of electric driving motors for a vehicle, each motor separately driving a vehicle wheel, means for connecting the motors in parallel to a source of supply, and automatic means responsive to a substantial decrease in the current in one of the motor circuits. for openingthe connection of all the motors to the source of supply.

3. In combination, a plurality of electric motors, a controller for connecting the motors to a source of supply in series or in parallel relation, means for automatically opening the connection to the source of supply upon the occurrence of abnormal circuit conditions in a portion of the motors in the parallel relation, and means for rendering the first mentioned means inoperative during the series-parallel transition.

4C. In combination, a plurality of electric motors, a series-parallel controller for the same having means for deenergizing a portion of the motors during the series-parallel transition, means for automatically delinergizing all the motors upon the occurrence of abnormal circuit conditions in a portion of the motors in the parallel relation, and means for rendering the latter means inoperative during the series-parallel transi tion.

5. In combination, a lurality of electric motors, a series parallel controller for the same having means for deenerglzmg a portion of the motors during theseries-parallel transition to change from the one relation to the other without opening the motor circuits means connecting the motors to a source 0 supply operated responsively to the cleanergization of a portion of the motors to auto-, matically deie'nergize ,allthe motors inrthe. parallel relation, and .means for rendering the latter means inoperative to open, the motor circuits during the series parallel transition.

6 In combination a plurality of electric motors, a series parallel controller for the same having means for deenergizing aportion of the motors during the series parallel transition, an automatic circuit breaker having a plurality of tripping coils each of .which 1s energized responsively to the current in one of the motor circuits to trip the breaker and open the connection to the source of supply upon the deenergization of another of the motors, and means tor pre venting tripping the. breaker during the series-parallel transition.

7. The combination with a series-parallel controller for a plurality of electric motors having means for deenergizing a, portion of the motors during the series-parallel transition to change from the one relationto the other withoutopening the motor circuits, of a circuit breaker in the circuit from the source of supply to the motors, tripping means for the circuit breaker operated responsively to a substantial change in the energization of a portion ofthe motors in the parallel arrangement, and means for. rendering the said tripping means inoperative during the series-parallel transition. t

8. In combination, a plurality of electric motors, a series parallel controller for changing the motors from the series to the parallel relationand vice versa without opening the motor circuits, an automatic circuit breaker in the circuit from the source of supply to, the motors, a plurality of trip i'ng coils for the breaker eaclibeing energizes responsively to the current in one of the motor circuits in the parallel relation and to the current in the circuit of all the motors in the series relation, the said coils normally neutralizing each other and having no tendency to trip the breaker until a portion of the motors is de'energized, andmeans for shunting the portion of the tripping coils which is energized during the series arallel transition to prevent the tripping oi the breaker during the said transition.

9. lhe combination with two electric driv- 'during the series parallel transition to change from one relation of the motors to the other without opening the motor circuits, a source of sup Iy forthe motors, an automatic circuit brea er in the circuit from the source of. supply to the motors, means for tripping the breaker comprising a plurality of coils, each in series with one of the motors, the said coils normally neutralizing each other and having no tendency to trip the breaker until one of the motors is deenergized, and means for-deenergizing both 0 f said coils during the series parallel tran- 10' SItlOIl.

In witness whereof, I have hereunto, set finy rhand this nineteenth day of February,

' JOHN G. CLENDENIN. 

